1. The problem statement, all variables and given/known data If you increase the charge on a parallel plate capacitor from 3μC to 9μC and increase the plate separation from 1mm to 3mm, the energy stored in the capacitor changes by a factor of... 2. Relevant equations U = 1/2QV or 1/2CV^2 3. The attempt at a solution I'm not sure which equation to even use, i'm not to great when it comes to differentiating between electric field and energy of the capacitor. I think I should probably use 1/2QV but i don't have a voltage to work with so i'm confused.